scholarly journals Updated evaluation of ϵK in the standard model with lattice QCD inputs

2018 ◽  
Vol 98 (9) ◽  
Author(s):  
Jon A. Bailey ◽  
Sunkyu Lee ◽  
Weonjong Lee ◽  
Jaehoon Leem ◽  
Sungwoo Park ◽  
...  
2018 ◽  
Vol 175 ◽  
pp. 13027 ◽  
Author(s):  
Bipasha Chakraborty ◽  
Christine Davies ◽  
Jonna Koponen ◽  
G Peter Lepage

he quark flavor sector of the Standard Model is a fertile ground to look for new physics effects through a unitarity test of the Cabbibo-Kobayashi-Maskawa (CKM) matrix. We present a lattice QCD calculation of the scalar and the vector form factors (over a large q2 region including q2 = 0) associated with the D→ Klv semi-leptonic decay. This calculation will then allow us to determine the central CKM matrix element, Vcs in the Standard Model, by comparing the lattice QCD results for the form factors and the experimental decay rate. This form factor calculation has been performed on the Nf = 2 + 1 + 1 MILC HISQ ensembles with the physical light quark masses.


2003 ◽  
Vol 18 (supp01) ◽  
pp. 1-26
Author(s):  
Richard Kenway

In the Standard Model, quarks and gluons are permanently confined by the strong interaction into hadronic bound states. The values of the quark masses and the strengths of the decays of one quark flavour into another cannot be measured directly, but must be deduced from experiments on hadrons. This requires calculations of the strong-interaction effects within the bound states, which are only possible using numerical simulations of lattice QCD. These are computationally intensive and, for the past twenty years, have exploited leading-edge computing technology. In conjunction with experimental data from B Factories, over the next few years, lattice QCD may provide clues to physics beyond the Standard Model. These lectures provide a non-technical introduction to lattice QCD, some of the recent results, QCD computers, and the future prospects.


2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
K. Azizi ◽  
A. T. Olgun ◽  
Z. Tavukoğlu

We present a study on the impact of scalar leptoquarks on the semileptonic decays of Λb, Σb, and Ξb. To this end, we calculate the differential branching ratio and lepton forward-backward asymmetry defining the processes Λb→Λl+l-, Σb→Σl+l-, and Ξb→Ξl+l-, with l being μ or τ, using the form factors calculated via light cone QCD in full theory. In calculations, the errors of form factors are taken into account. We compare the results obtained in leptoquark model with those of the standard model as well as the existing lattice QCD predictions and experimental data.


2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Vincenzo Cirigliano ◽  
Emanuele Mereghetti ◽  
Peter Stoffer

Abstract We define a regularization-independent momentum-subtraction scheme for the C P -odd three-gluon operator at dimension six. This operator appears in effective field theories for heavy physics beyond the Standard Model, describing the indirect effect of new sources of C P-violation at low energies. In a hadronic context, it induces permanent electric dipole moments. The hadronic matrix elements of the three-gluon operator are non-perturbative objects that should ideally be evaluated with lattice QCD. We define a non-perturbative renormalization scheme that can be implemented on the lattice and we compute the scheme transformation to $$ \overline{\mathrm{MS}} $$ MS ¯ at one loop. Our calculation can be used as an interface to future lattice-QCD calculations of the matrix elements of the three-gluon operator, in order to obtain theoretically robust constraints on physics beyond the Standard Model from measurements of the neutron electric dipole moment.


2018 ◽  
Vol 175 ◽  
pp. 14015 ◽  
Author(s):  
Yong-Chull Jang ◽  
Weonjong Lee ◽  
Sunkyu Lee ◽  
Jaehoon Leem

We report updated results for ɛK, the indirect CP violation parameter in neutral kaons, which is evaluated directly from the standard model with lattice QCD inputs. We use lattice QCD inputs to fix [see formula in PDF], and mc(mc). Since Lattice 2016, the UTfit group has updated the Wolfenstein parameters in the angle-only-fit method, and the HFLAV group has also updated |Vcb|. Our results show that the evaluation of ɛK with exclusive |Vcb| (lattice QCD inputs) has 4.0σ tension with the experimental value, while that with inclusive |Vcb| (heavy quark expansion based on OPE and QCD sum rules) shows no tension.


2016 ◽  
Vol 93 (11) ◽  
Author(s):  
A. Bazavov ◽  
C. Bernard ◽  
C. M. Bouchard ◽  
C. C. Chang ◽  
C. DeTar ◽  
...  

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